Physical vapor deposition involves providing a source material and a workpiece to be coated in a deposition chamber. The source material is converted into vapor by an energy input, such as heating by resistive, inductive, or electron beam means.
Cathodic arc vapor deposition involves placement of a source material and a workpiece to be coated in a deposition chamber. The negative lead of a direct current (DC) power supply is attached to the source material (hereinafter referred to as the “cathode”) and the positive lead is attached to an anodic member. In many cases, the positive lead is attached to the deposition chamber, thereby making the chamber the anode. An arc-initiating trigger, at or near the same potential as the anode, contacts and moves away from the cathode. When the trigger is in close proximity to the cathode, the difference in potential between the trigger and the cathode causes an arc of electricity to extend therebetween. As the trigger moves further away, the arc jumps between the cathode and the anodic chamber. The exact point, or points, where an arc touches the surface of the cathode is referred to as a cathode spot. Absent a steering mechanism, a cathode spot will move randomly about the surface of the cathode.
Current cathodic arc systems use cathodes with a fixed location within a coating chamber. Consequently, evaporation occurs at a generally fixed location within the constraints of the cathode geometry. As a result, deposition occurs non-uniformly at different places in the chamber, so that a coating deposited on a workpiece may have a non-uniform thickness depending on the fixed orientation of the cathode.